I bought a Beretta Silver Snipe used in 1966 and the side of block engraved '12 Ga' but on the ears of the top of the block is stamped '20 Ga' which begs the obvious question of Why and How come?

It could be that the gun was madeon a 20 guage frame with the 12 guage barrel. I would have the chamber checked by a gunsmith. If this is not the case it could be dangerous to fire it. Please be careful.